package model;
import java.util.Iterator;
import java.util.List;
import java.util.Random;


public class Wolf extends Animal{

// Characteristics shared by all Wolves (class variables).
    
    // The age at which a fox can start to breed.
    private static final int BREEDING_AGE = 20;
    // The age to which a wolf can live.
    private static final int MAX_AGE = 200;
    // The likelihood of a wolf breeding.
    private static final double BREEDING_PROBABILITY = 0.06;
    // The maximum number of births.
    private static final int MAX_LITTER_SIZE = 1;
    // The food value of a single rabbit. In effect, this is the
    // number of steps a wolf can go before it has to eat again.
    private static final int RABBIT_FOOD_VALUE = 4;
    private static final int FOX_FOOD_VALUE = 9;
    // A shared random number generator to control breeding.
    private static final Random rand = Randomizer.getRandom();
    
    // Individual characteristics (instance fields).
    // The wolf's food level, which is increased by eating rabbits.
    private int foodLevel;

    /**
     * Create a wolf. A wolf can be created as a new born (age zero
     * and not hungry) or with a random age and food level.
     * 
     * @param randomAge If true, the wolf will have random age and hunger level.
     * @param field The field currently occupied.
     * @param location The location within the field.
     */
    public Wolf(boolean randomAge, Field field, Location location)
    {
        super(field, location);
        if(randomAge) {
            setAge(rand.nextInt(MAX_AGE));
            foodLevel = rand.nextInt(RABBIT_FOOD_VALUE);
        }
        else {
            setAge(0);
            foodLevel = RABBIT_FOOD_VALUE;
        }
    }
    
    /**
     * This is what the wolf does most of the time: it hunts for
     * rabbits. In the process, it might breed, die of hunger,
     * or die of old age.
     * @param field The field currently occupied.
     * @param newFoxes A list to return newly born foxes.
     */
    public void act(List<Actor> newWolves)
    {
        incrementAge();
        incrementHunger();
        if(isAlive()) {
            giveBirth(newWolves);            
            // Move towards a source of food if found.
            Location newLocation = findFood();
            if(newLocation == null) { 
                // No food found - try to move to a free location.
                newLocation = getField().freeAdjacentLocation(getLocation());
            }
            // See if it was possible to move.
            if(newLocation != null) {
                setLocation(newLocation);
            }
            else {
                // Overcrowding.
                setDead();
            }
        }
    }
    
    /**
     * Make this fox more hungry. This could result in the fox's death.
     */
    private void incrementHunger()
    {
        foodLevel--;
        if(foodLevel <= 0) {
            setDead();
        }
    }
    
    /**
     * Look for rabbits adjacent to the current location.
     * Only the first live rabbit is eaten.
     * @return Where food was found, or null if it wasn't.
     */
    private Location findFood()
    {
        Field field = getField();
        List<Location> adjacent = field.adjacentLocations(getLocation());
        Iterator<Location> it = adjacent.iterator();
        while(it.hasNext()) {
            Location where = it.next();
            Object animal = field.getObjectAt(where);
            if(animal instanceof Fox) {
                Fox fox = (Fox) animal;
                if(fox.isAlive()) { 
                    fox.setDead();
                    foodLevel = FOX_FOOD_VALUE;
                    return where;
                }
            } else if(animal instanceof Rabbit) {
                Rabbit rabbit = (Rabbit) animal;
                if(rabbit.isAlive() && foodLevel < RABBIT_FOOD_VALUE) { 
                    rabbit.setDead();
                    foodLevel = RABBIT_FOOD_VALUE;
                    return where;
                }
            }
        }
        return null;
    }

	@Override
	public boolean isActive() {
		// TODO Auto-generated method stub
		return true;
	}

	@Override
	int getMaxAge() {
		return MAX_AGE;
	}

	@Override
	int getBreedingAge() {
		return BREEDING_AGE;
	}

	@Override
	double getBreedingProbability() {
		return BREEDING_PROBABILITY;
	}

	@Override
	int getMaxLitterSize() {
		return MAX_LITTER_SIZE;
	}
	
	@Override
	Animal newYoung(Location location) {
		return new Wolf(false, getField(), location);
	}

}
